1. Field of the Invention
This invention relates generally to an anchor boring unit to be attached to a section advance machine using in mining operations.
2. Description of the Background
Advance machines are used in section advances in underground working, for example, in coal mining. Mountain anchors or rock bolts or rock anchors are placed to secure the roof of the tunnel. This roof securing should take place as close as possible to the position front of the advance.
The mounting of anchor boring units directly on the advance machine is already known, and such an anchor boring unit is described in German Patent DE-PS 31 08 877. This document shows an advance machine in which boring devices are movable in a peripheral direction and are capable of swivelling or moving longitudinally by being mounted on a yoke. It is thereby possible to seat the rock anchors close to the position front of the advance. Nevertheless, it is not possible to alter the section profile of the advance with this system, because the boring devices have a relatively small thrust and, more importantly, the yoke requires a minimum height of the section that is considerably greater than what would normally be necessary for the advance machine itself. This is especially disadvantageous in the mining of ore or coal, because it is not possible to adapt the section height to the deposit thickness, and consequently either much barren rock must be mined, or it is not possible to utilize all of the deposit thickness that is present.
In addition, movement of the rock anchor boring units to the side is limited by the mining machine itself. Thus, if it is also necessary to secure the vertical side walls by anchors, a separate carrier with a second yoke on which other rock anchor boring devices are movably attached must be pulled along by the mining machine, when following the proposal according to DE-PS 31 08 877. On this second yoke, the outermost boring device can in all cases be run deeper downward, and the wall can thereby also be assured, however, this securing of the wall takes place at quite a distance from the position front.
Another rock anchor boring unit attached to a section advance machine is shown in German Patent DE-PS 33 34 975, in which it is only possible to seat two anchors into the roof. These two anchors can only be located to the left and right of the advance machine in all cases, and the anchors are not close to the position front.
An anchor boring unit that is attached to a movable cutting unit is shown in German Patent DE-PS 34 28 358. With that apparatus, it is only possible to insert anchors into the roof and, moreover, the cutting process necessarily halts during the anchor placement.
German Patent DE-OS 35 23 035 describes another section advance machine with installed anchor boring units, however, once again only the roof can be anchored.
In German Patent DE-OS 36 34 502, assigned to the assignee hereof, an anchor boring unit is described that is designed to operate telescopically and therefore permits a better adaptation of the boring unit height to the deposit thickness than the anchor boring units hitherto described. The unit according to DE-OS 36 34 502 is somewhat movable around a horizontal axis, so that it is possible to seat several anchors in the roof next to each other with the same unit.